<html>
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 <title>js</title>
 </head>
 <script language="javascript">
 function aa(){
     var r=document.getElementsByName("r"); 
     for(var i=0;i<r.length;i++){
          if(r[i].checked){
          alert(r[i].value+","+r[i].nextSibling.nodeValue);
        }
     }      
 }
 </script>
 <body>
 <form name="form1" method="post" action="">
 <input type="checkbox" name="r" value="1">a<br>
 <input type="checkbox" name="r" value="2">b<br>
 <input type="checkbox" name="r" value="3">c<br>
 <input type="checkbox" name="r" value="4">d<br>
 <input type="checkbox" name="r" value="5">e<br>
 <input type="checkbox" name="r" value="6">f<br>
 <input type="checkbox" name="r" value="7">g<br>
 <input type="checkbox" name="r" value="8">h<br>
 <input type="checkbox" name="r" value="9">i<br>
 <input type="checkbox" name="r" value="10">j<br>
 <br>
 <input type="button" onclick="aa()" value="button">
 </form>
 </body>
 </html>